Paper in Press
JOURNAL OF GEOPHYSICAL RESEARCH, doi:10.1029/2011JE003816
Possible evidence of palaeomarsquakes from fallen boulder populations, Cerberus Fossae, Mars.
- Boulder populations may indicate localised ground shaking
- Marsquakes may be driven by volcanism
- Volcanism has implications for life
In order to differentiate between boulder avalanche deposits triggered by temperature/climate controlled melting of ice, or triggered by ground shaking produced by palaeomarsquakes, spatial variation in boulder-size populations has been measured from HiRISE images along Cerberus Fossae, one of the youngest fracture/graben systems on the martian surface. The boulders have fallen from < ~500 m high fault-controlled cliffs, and rolled and bounced across relatively coarse grained sediment forming colluvial fans. The boulders have left trails in the dust in some cases, coming to rest on relatively-fine grained aeolian sediment. The boulder size distribution varies along graben contrary to what would be expected if boulder falls had been liberated by temperature/climate controlled melting of ice. Boulder size data peak close to the centre of the fault system, decreasing along strike. The widths and density per km of trails made in dust by boulders is also greatest at the centre of the fault, decreasing along strike. Furthermore, evidence for relatively-recent surface faulting of colluvial slopes along the fault-controlled cliffs is confined to between 156.5o and 158.2o, although possibly extending as far as c. 159.5o with uncertainty due to lack of HiRISE coverage. We interpret the above as consistent with observations of terrestrial earthquake triggered boulder avalanches where boulder sizes decrease away from the epicentre and surface faulting. We discuss the implications of possible marsquakes along Cerberus Fossae in terms of active faulting associated with dike emplacement that is sub-radial to the Elysium Mons volcano.
Received 11 February 2011; accepted 14 December 2011.
Citation: (2012), Possible evidence of palaeomarsquakes from fallen boulder populations, Cerberus Fossae, Mars., J. Geophys. Res., doi:10.1029/2011JE003816, in press.